This invention relates to systems and methods for processing and collecting blood, blood constituents, or other suspensions of cellular material.
Today people routinely separate whole blood, usually by centrifugation, into its various therapeutic components, such as red blood cells, platelets, and plasma.
Conventional blood processing methods use durable centrifuge equipment in association with single use, sterile processing systems, typically made of plastic. The operator loads the disposable systems upon the centrifuge before processing and removes them afterwards.
Conventional blood centrifuges are of a size that does not permit easy transport between collection sites. Furthermore, loading and unloading operations can sometimes be time consuming and tedious.
In addition, a need exists for further improved systems and methods for collecting blood components in a way that lends itself to use in high volume, on line blood collection environments, where higher yields of critically needed cellular blood components, like plasma, red blood cells, and platelets, can be realized in reasonable short processing times.
The operational and performance demands upon such fluid processing systems become more complex and sophisticated, even as the demand for smaller and more portable systems intensifies. The need therefore exists for automated blood processing controllers that can gather and generate more detailed information and control signals to aid the operator in maximizing processing and separation efficiencies.
The invention provides systems and methods for processing blood and blood constituents that lend themselves to portable, flexible processing platforms equipped with straightforward and accurate control functions.
More particularly, the invention provides blood processing systems and methods, which employ two sensors, one to detect a condition of plasma exiting a separation device and another sensor to detect a condition of a cellular component exiting the separation device. The first sensor detects, e.g., contamination of the plasma due to presence of unwanted cellular components. The second sensor detects, e.g., dilution of the cellular component due to presence of plasma. Blood processing parameters are carried out based, at least in part, by conditions detected by one or both of the sensors.
In one embodiment, the first sensor detects an over spill condition along the low-G wall of a centrifugal separation chamber, where plasma resides for collection. Over spill sensing makes possible the collection of plasma, if desired, free or essentially free of contamination by unwanted cellular species, like platelets or leukocytes or red blood cells. Over spill sensing also makes possible the collection of red blood cells, if desired, free or essentially free of contamination by unwanted cellular species, like platelets or leukocytes. Over spill sensing also makes possible the collection of a buffy coat rich in platelets and free or essentially free of contamination by red blood cells.
The second sensor detects an under spill condition along the high-G wall of the a centrifugal separation chamber, where red blood cells reside for collection. Under spill sensing makes possible the collection of red blood cells of high hematocrit, by controlling dilution by plasma.
By providing both over spill and under spill sensing capabilities, the invention enables diverse collection procedures to be carried out by the same blood processing system, with each procedure achieving optimized collection efficiencies while minimizing contamination.
One aspect of the invention provides blood separation systems and related methods which convey whole blood through an inlet line into a device which, in use, operates to separate the whole blood into red blood cells and plasma. The systems and methods include a plasma collection line to convey a flow of plasma from the device and a red blood cell collection line to convey a flow of red blood cells from the device.
According to this aspect of the invention, the systems and methods include first and second sensing assemblies. The first sensing assembly includes a first sensor in the plasma collection line. The second sensing assembly includes a second sensor in the red blood cell collection line. The first sensor operates to detect presence of at least one cellular blood component in the flow of plasma and to generate a first output. The second sensor operates to detect red blood cell hematocrit in the flow of red blood cells and to generate a second output. The systems and methods include a controller operating to control flows in the plasma collection line based upon the first output, with the objective of preventing contamination of the component targeted for collection by one or more undesired blood components. The controller also operates to control flows in the red blood cell collection line, to prevent dilution of the red blood cells by plasma, if desired.
The component targeted for collection can vary. It can, for example, comprise plasma, or red blood cells, or both. It can also comprise a buffy coat rich in platelets. The undesired cellular species to be detected by the first sensor likewise vary according to which component is targeted for collection.
For example, when plasma is targeted for collection, the undesired cellular species to be detected by the first sensor include platelets, leukocytes, and red blood cells. When red blood cells are targeted for collection, the undesired cellular species to be detected by the first sensor include platelets and leukocytes. When red blood cells are targeted for collection, the second sensor also prevents plasma dilution of the red blood cells, thereby keeping hematocrit at or above a desired level.
When buffy coat rich in platelets is targeted for collection, the undesired cellular species to be detected by the first sensor include red blood cells.
In one embodiment, the plasma collection line includes a plasma pump operable to provide variable flow rates. The controller operates the plasma pump based upon the first and second outputs.
In one embodiment, the first sensor operates to detect platelets in the flow of plasma. The first sensor also operates to detect red blood cells in the flow of plasma. The systems and methods condition the first sensor to differentiate between platelets and red blood cells. The systems and methods thereby make possible the use of the first sensor in association with procedures that collect red blood cells, or plasma, or buffy coat, or combinations thereof.
In one embodiment, the controller includes an input for selecting either a first blood collection protocol, e.g., to collect plasma, or a second blood collection protocol, e.g., to collect red blood cells. The systems and methods operate the first sensor to detect platelets in the flow of plasma when the first blood collection protocol is selected and operate the first sensor to detect red blood cells in the flow of plasma when the second blood collection protocol is selected.
In one embodiment, the controller includes an input for selecting another blood collection protocol, e.g., to collect the buffy coat layer. The systems and methods operate the first sensor to detect an interface between the buffy coat layer and the plasma and an interface between the buffy coat layer and the red blood cells.
Another aspect of the invention a blood separation system comprising a device for separating whole blood into red blood cells and plasma. The system includes a sensing assembly outside the device, which comprises a first sensor to sense a characteristic of plasma and a second sensor adjacent to the first sensor to sense a characteristic of red blood cells. A fluid circuit is coupled to the device and includes a plasma collection tube for conveying a flow of plasma from the device and a red blood cell collection tube for conveying a flow of red blood cells from the device. According to this aspect of the invention, the tubes are held in a fixture, which is movable into releasable engagement with the sensing assembly. The fixture holds the plasma collection tube and the red blood cell collection tube in adjacent sensing alignment with, respectively, the first sensor and the second sensor.
In one embodiment, the fluid circuit includes a whole blood inlet tube for conveying a flow of whole blood into the device. In this embodiment, the fixture also holds the whole blood inlet tube. The fixture thereby serves to gather and hold the whole blood inlet tube, the plasma collection tube, and the red blood cell collection tube in a bundle.
The fixture can comprises an integral part of the fluid circuit or a separately fabricated part of the fluid circuit.
Other features and advantages of the inventions are set forth in the following specification and attached drawings.